Metals: Occurrence, Processing & Extraction

Instructor: Julie Zundel

Julie has taught high school Zoology, Biology, Physical Science and Chem Tech. She has a Bachelor of Science in Biology and a Master of Education.

While metals are a huge part of our lives, we probably don't think much about where they come from. This lesson explores where ores can be found and how they are processed in order to separate out the parts of the ore that can be utilized.

VE Note: This lesson is a text-to-video conversion. Please feel free to take liberty in bringing this piece to life for our students. Thanks!

Title Bar: MINING AND ORES DEFINED

Take a look around you and count up how many things contain metal: silverware, soda cans, necklaces, mailboxes, cars… the list is long! So, while metal is a huge part of our lives, how much do you know about where it comes from?

Our love of metal dates back thousands of years. Prehistoric man found native metals, or metals that are in their natural state, and used them to make primitive tools and decorations.

Today, we have the knowledge and the technology to go after more than the native metals our prehistoric ancestors sought, which is good news, since we use metals for everything!

Most of what we use today comes from mining, which is the process of obtaining valuable materials, like metals, from the Earth. Little did prehistoric man realize, the native metals were just a tiny fraction of what could be found and used. Mines look for ores, which are naturally-occurring substances that can contain metals.

Before we delve into how ore is separated, let's check out where metals are found.

Title Bar: LOCATION & OCCURRENCE

Geologists are always on the lookout for metals, but just because they are found, doesn't mean they will be mined. For example, the ore needs to be located in an area that is reasonably accessible. The ore's grade, or how much of the metal is in the ore, must be high enough to make mining profitable. And the deposit needs to be large enough to make building a mine worth the cost and effort.

Ores are not evenly distributed across the world, with some regions having higher concentrations. In the Southwestern United States, for example, there are numerous copper deposits. Or Southeastern Asia has several tin deposits and Northeastern Australia has high numbers of lead and zinc deposits.

So, why are some regions better than others? Certain ores are more likely to be found in specific types of rock. For example, iron ore is usually found in sedimentary rock, where deposits were formed long ago. This occurred when photosynthetic organisms released oxygen into the water and the oxygen combined with the iron to form iron deposits. Like iron, each type of ore has its own story that created the deposit.

Based on the occurrence and accessibility of ores, some countries produce more metals than others. For example, China is a major producer of metals and between 2005 and 2009 produced 52% of the world's aluminum, 23% of the world's gold, and 48% of the world's iron ore.

Title Bar: PROCESSING & EXTRACTION

Now that you have a better idea about where some of the ore can be found, let's check out how to separate the ore. Remember, the ore contains rocks, sediment and other materials along with the metal. the part of the ore that doesn't have value is termed gangue, and mining companies have several ways to separate the gangue from the metal.

Let's begin with levigation, which uses water to separate out the gangue. More specifically, the ore is mixed with water, the metals sink, and the gangue is washed away. This works best when the ore is heavier than the gangue.

Magnetic separation works by using a material's magnetic properties to separate the metal from the gangue. Here, the ore is ground down and goes on a magnetic roller, which separates out the magnetic materials from the non-magnetic materials. This works best with iron, chromite. and tin.

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